Band saws are often used for cutting curves of large radius in Lucite methyl methacrylate resin. Because of the length of band saw blades, they dissipate heat more rapidly than do circular saws. Accordingly, they operate at lower temperatures and...

Text from back of image: "Photo shows a new helicopter invented by the Spanish engineer Don Juan Dela Cierva and called the autogiro, while it was being tried out recently at the Cuatro Vientos Airdrome in France when it made the record breaking...